Molly-
Practical Sailor reviewed the boat & gave it high praise, a long time ago and in their "Practical boat Buying" volume 1.
Among the differences the "later" models (they don't indicate Marks) had added lower forward shrouds to reduce mast pumping. Changed the mast base to add fittings to make it easier to lead all lines aft. And eventually moved the traveler to the cabin top in 1982, apparently to preserve the helmsman's head.

In 1976 the forward anchor well was added. Pre-1982, the top of the ice box was not well insulated lathough the box itself was. post-82, the top was also insulated.

Base engine was the A4 with a Volvo diesel option, then both were replaced by the MD7A and finally a Westerbeke in 1981. So if you don't want Volvo, you will be getting a 1981+ boat or a repowered one.

Those Volvos are capable of running a very long time, but ANY raw-water-cooled engine that has been used in salt water all this time my have extensive salt corrosion and literally be rusting away inside. Typically you can check that by removing the cooling pump or somtimes the exhaust manifold itself, in order to see if the engine has been eaten out. That's about the only thing that really will kill them.

As compared to Westerbleak [sic] sho never really BUILD engines, they assemble parts supplied by the lowest bidder. So one "WB" may be a British Leyland engine while another comes from Japan...some sleuthing may be required.

Basically they give the boat a gold star, and differences (moving the traveler, insulating the icebox, adding the shrouds) are all fairly simple changes an owner can make. Choice of engine and anchor well are about the only things you'd want to make sure were already done, and it sounds like "post 82 boat" would make that all happen for you.

I never met a Sabre I didn't like, or find some really small feature that tipped me off, the folks who were building it, spent plenty of their own time appreciating boats.